I finally got my 69 Road Runner to the track today after putting the exhaust manifolds back on it last year.

My old set up was a pair of Hooker Comp headers with 1 7/8' primaries, a 3" collector, compression bent 2.5" exhaust exiting at the rear bumper (non h-pipe) and a pair of two chamber Flowmasters. The new set up is my original hi-po exhaust manifolds with just the casting flash cleaned up and a 2.5" TTI H-pipe kit exiting at the rear bumper. I'm running the Dynomax Super Turbo's that came with the kit. Both set ups used factory-ish tips.

The car weighs 3466 without me in it. Has a 400 based 470 with around 9.65 compression, 213 motor home heads with big valves and pocket porting, an Eddie Performer RPM intake, 850 street HP and an Xtreme Energy .488/.491" lift cam with 230/236 duration at .050" with 110 LSA (not the best for exhaust manifolds). I run a pair of Micky Thompson Sportsman Pros and have to roll into the throttle at the line.

Since the last time I raced with the headers I added a drop base air cleaner housing which allowed me to fit almost another half inch of air filter under the stock un-silenced air cleaner lid and I also added a 50cc accelerator pump to the front bowl which was needed due to the size of the pump squirter I run- just never got around to it with the old set up. I had an intermittent flat spot off idle where the car would lean out for 100-200 rpm which was verified on a dyno.

Unfortunately the track was not there today and I did not get many clean runs without spinning. Both slips were the first runs right off of the trailer. Also, when I was last there the conditions were perfect and although today was pretty good, it was not as good as the last time I was there. One guy commented on my last outing that the DA was the best he'd ever seen it at Trails.

So, this test was not truly apples to apples but, it gives you a good idea. The MPH is the most telling but, I wonder with the additional air the car is probably getting with the new filter, if the car wants more jet and maybe some of the MPH would come back. I changed nothing on the car when I ran it today. I'd like to get back to the dyno and check things out with the new changes or get a wideband. The car was tuned with the headers and I'm sure the manifolds and other changes on the car probably want something different.

Anyway, 12.25 with the headers and old exhaust which was the best run ever vs. 12.48 which was the best today with the manifolds and TTI exhaust.

For racing once every year or two, I must say that I do pretty good on the tree.

Oh, by the way, Today you would of thought Hellcats were Honda Civics. I think there were like 6 there. It was an overall Mopar day. Lots of Nice Cuda's, 65 Coronets, a 64 Dodge, A nasty looking 70 Super Bee. Just a lot more Mopars than what you normally see at an all brands event.

Thanks for posting.

The DA for the two track days is nearly identical, about 1050 ft. so the numbers are actually comparable.

Pretty cool. Thanks for Posting

104 is good enough for 12's. unbolt the exhaust and you'll pick up 2 more tenths. (at least)

I think you mssed it. Already at 12.5 at 108 mph

whoops... well still uncap it and see if you can pick up a few more.

I'm actually interested in the FAST class; just taking my time getting there.

I really don't have too many miles on the current set up. I think I'm just going to keep tuning and messing with what I have for the foreseeable future but, when she's ready to be freshened up, I think I'm going to get more serious about building it for the class.

I still have other aspects like the suspension I can mess with in the mean time. I thought about a cam swap in the future or I have a set of low mile 906's in the basement and 2 stock intake manifolds in the garage; I've thought about sending them off to Mr. Porter for some port work and throwing those on for a few years and see what I can do.

I know I won't be competitive in the class with a wedge but, I'd really like to have something similar to Harry Chargois' old Red Super Bee.

I do still want it to be streetable too so; it won't be a max effort deal.

I think the next step you should try is the oem intake.
Those things are awful, and are the biggest hurdle to overcome in that combo.

I know of a couple FAST guys who had more serious builds than yours that didn't run much better. All in all...... That's running pretty good.

The other side of the coin is, it shows that headers are still a pretty cheap and effective way to gain performance.
I have to believe if the headers had the benefit of the tti mandrel bent tubing and an h or x pipe behind them, there might have been a little more ET to be had.

Where's Cab?? Remember Pat Melendys Roadrunner going in the mid-high 12's with exhaust manifolds back in 84-ish?? Guy was ahead of his time...lol. I asked him one time "why"? He said "because I want to". Lol...

Don't we have a member on here that has a yellow 68 Dart that goes 10's with a stick and exhaust manifolds??

there was a 69 superbee A12 car local that was bone stock original paint 4spd 4.10dana that ran 13.0s untouched points dist and all.

On a FAST legal stroker build, the 6bbl is 70hp+ better than the iron 4bbl intake with a new 800avs edelbrock carb.

Removing the 800avs and installing a correct AVS from a 383 cost another 30+hp.

WOW well that explains why it ran so hard............i was still impressed with it for not having any tricks ....it would mph 110ish

Would you be interested in porting the intake for me? I know Harry tried to replicate the contours and volume of the DP4B intake. Would you try something different or do the same?

I was speaking with a guy at the track with a newer Challenger and I told him about my switch from headers to manifolds and before I could say anything else he asked "why"? I told him about my interest in the FAST class which he'd not heard of before. You could tell he thought I was odd for doing what I'm doing.

I love the class. I really want to get my car in the 11.60-70 range and I'll be happy.

I think another car will be bought if I want to go any faster.

I built my 500 motor in a way that if I wanted to go FAST, I would have a good starting point. As currently built, swapping my Mopar (Eddy) heads for 915s would give me a 12.5:1+ compression ratio. The part holding me back is the factory intake manifold. No matter what you do to the motor, that intake get you diminishing returns pretty quick, and a lot of work and money for very small incremental improvements. I'm actually surprised that Dwayne says it is a 70 hp hit from the 6 bbl. I thought it would be more.

Instead I went with a stock looking light. I don't pass it off as stock, but honestly, it is surprising how many people don't know (or really care) one way or the other. The advantage is that it runs on pump gas and can drive it anywhere any time. My motor in your car with the track conditions you had last weekend would run low 11s at about 125 mph with the stock converter, full automatic shift and 3.23 gears.

Of course, if the goal is to race in the class, you have little choice.

I appreciate your input.

What cam do you run in yours?

It is a relatively small street type solid roller by Comp and speced by Dwayne (fast68plymouth). Give him a call when you're ready, he has experience in these applications.

I was going to guess 0.3 ET change, and you lost less than that. So you did pretty good IMO. Maybe the exhaust pipe differences helped with the exhaust manifolds.

Did you gasket match the manifolds ? the last set I worked on the openings were almost an 1/8" smaller than the gasket which is what the heads were matched to.

I have a manifold that Dwayne worked on for a low deck ... and an acid ported 70 383 intake ... plus a set of extrude honed, jet hot coated A body 383 Exh manifolds ...

my FAST builds never materialized ...